VSCODE extension onwillrename

Question

we are doing our own extension(vscode 1.66, win10).

1.) we want to prevent a rename of files in the explorer if the extension of the file is wrong or the filename is getting too long (transmit it to the mainframe with zowe afterwards).

  workspace.onWillRenameFiles((e: FileWillRenameEvent) => {})

i could do a dispose afterwards (when assigning) but i could not do it inside the eventlistener.

2.) nearly the same as number 1, we want to prevent a file delete under certain conditions.

Thank you, it seems a lot of lacking knowledge here.